I. Isolation and Identification of the Carcinogen, N-Hydroxy-2- Fluorenylacetamide (N-hydroxy-2-FAA) and related compounds by high-performance liquid-liquid chromatography (LLC). A new method has been worked out for the isolation, identification and the measurement of N-hydroxy-2-FAA and related compounds by LLC. The method utilizes Carbowax 400/Parosil as the stationary phase and diethylether as the mobile phase. . N-Hydroxylation of N-2-and N-3fluorenylacetamide by hepatic microsomes of the Rat and Guinea Pig. The microsomal N-hydroxylation of 2-FAA, a carcinogen, and of 3-FAA, a non-carcinogen, has been studied in the rat and guinea pig. The rat and the guinea pig N-hydroxylated 2-FAA although at widely differing rates. Inducibility of N-hydroxylation by 3-MC and phenobarbital, inhibition by CO suggests that the reaction is catalyzed by cytochrome p-450. 3-FAA was a poor substrate for N- hydroxylation by hepatic microsomes of either species. III. Protein Modification by Activated Carcinogens. Because of increasing evidence that acetyltion of nuclear proteins affects transcription, we are investigating whether N-acetoxyoxy-2-FAA modifies histones of calf-thymus and of rat-liver by acetylation or by arylamidation. The evidence indicates that the acetylation of various purified histone fractions by N-acetoxy-2-FAA is 2-4-fold greater than arylamidation. The identification of the acetyl acceptor in histones is in progress. IV. Synthesis of N-hydroxy-3-(9-3H) fluorenylacetamide. N-hydroxy-3-fluorenylacetamide is a potent mammary carcinogen for the rat by several routes of administration. The mechanism of action of n-hydroxy-3FAA appears to be distinctly different from that widely accepted for N-hydroxy-2-FAA. However, information on the interaction of N-hydroxy-3-FAA with macromolecules, requisite for elucidation of its action, is lacking because the compound was not available in labelled form. A synthesis for the selective tritiation of carbon atom-9 of n-hydroxy-3-FAA has been devised. The key step consists of the hydrogenolysis, with LiAL 3H4-AlCl,, of 3-aminofluoren-9- one to 3-(9-H3) fluorenamine. The undersigned agrees to accept responsibility for the scientific and thechnical conduct (Text Truncated - Exceeds Capacity)